The present invention relates to a leveling system for a vehicle, and more particularly to a valve body for distributing air to suspension elements.
Conventional leveling systems are installed in a wide variety of vehicles ranging from passenger cars to semi-trucks and semi-trailers. The larger leveling systems typically include pneumatic suspension elements, such as shocks or air springs, that can be inflated or deflated to control the height of the frame with respect to the axle. For example, on semi-trailers, heavy loads can cause a suspension to sag, thereby decreasing the distance between the frame and the axle. Accordingly, the ride height of the trailer, that is, the distance between the trailer bed and the ground, may be reduced. In conventional leveling systems, the ride height of the trailer may be adjusted by inflating or deflating the pneumatic suspension to compensate for the load. Specifically, when the ride height of a trailer has been affected by a heavy or light load, the suspension elements can be inflated or deflated to return the trailer to the desired ride height.
In leveling systems of the prior art, the height of the suspension is controlled by mechanical height control valves including a valve assembly and a valve body. The valve assembly senses the fluctuations in the ride height due to loading and controls the inflation/deflation of the suspension elements through the valve body. Typically, the valve body is located within the leveling circuit between a source of compressed air and the suspension elements. During operation, the valve body typically is in a neutral or xe2x80x9cclosedxe2x80x9d mode. Accordingly, air cannot enter or leave the leveling circuit. However, due to fluid communication between suspension elements on opposite sides of the vehicle via the valve body, air may flow from a left side element to a right side element when the left side element is excessively loaded-this is called xe2x80x9cside-to-sidexe2x80x9d air transfer. Obviously, air may flow from right to left when the right side is excessively loaded as well.
Illustrated in FIG. 1 is an uneven loading situation resulting in side-to-side air transfer. A vehicle 110 traversing a corner has a tendency to tilt or roll outward away from the xe2x80x9ccenterxe2x80x9d of the corner, due to centrifical force. During this tilting action, the right side elements 104 are excessively compressed by the load being shifted outward. Due to the fluid communication between the left 102 and right 104 side suspension elements, air is forced from right side suspension elements 104, travels through the valve body 108, and into the left side suspension elements 102. As a consequence, the left side suspension elements 102 extend and exacerbate the tilt or roll of the vehicle. Further, given the advent of larger airflow lines used in conventional leveling circuits to promote quicker inflation/deflation of air suspension elements, side-to-side air transfer is substantially increased.
Illustrated in FIG. 2 is a valve body 115 of the prior art that attempts to correct side-to-side transfer of air by placing a passive restrictive element 112 within the valve body 115. Although the use of the restrictive element does limit the side-to-side transfer of air A during cornering, it creates a variety of problems. First, the restrictive element restricts (a) dumping of air from the suspension elements, through the dump port 122 during deflation, and (b) injection of air into the valve body 115 via the supply port 126, and consequently into the suspension elements, during inflation. Second, dirt or debris accidentally entering the interior portion of the valve body, may become lodged between the restrictive element and the valve body to substantially impede airflow through the valve body. Moreover, to remove the debris, the valve body must be detached from the valve assembly.
The aforementioned problems are overcome by the present invention wherein the valve body of a height control leveling system is provided with devices to actively restrict side-to-side transfer of air between suspension elements.
In one embodiment, a restrictive airflow disc is positioned in each of the two suspension ports of a valve body to actively restrict side-to-side air transfer. The airflow disc is a thin, flat circular plate with an orifice through its center, and bypass orifices disposed around the disc""s circumference. A coil spring is attached to a first side of the disc, and a sealing element is disposed around the central orifice on a second side of the disc. In each of the suspension ports, the coil spring abuts an internal seat of the valve body and forces the sealing element in sealing engagement with a suspension fitting associated with the air supply line coupled to the suspension port.
The disc has two modes; restrictive and non-restrictive. The disc attains a non-restrictive mode when air, forcibly exhausted from an air spring, presses against the disc and compresses the coil spring. The compression of the spring causes the disc to move away from the suspension fitting, and disengages the sealing element from the suspension fitting, thereby allowing air to exhaust into the valve body through the bypass orifices as well as the central orifice. The disc attains a restrictive mode when air is injected into the suspension port from the valve body. The sealing engagement of the sealing element against the suspension fitting is reinforced so that air enters the suspension lines through the central orifice alone. Thus, when air is forced from a compressed suspension element during cornering to the valve body through a suspension port, the airflow disc associated with the suspension port connected to the compressed element attains a non-restrictive state; and air flows freely into the valve body. Conversely, when air passes through the valve body into the suspension port associated with the suspension element on the opposing, unloaded side of the vehicle, the airflow causes the airflow disc in that suspension port to substantially obstruct the suspension port, so that air cannot pass freely to the unloaded suspension port. Thus, at least for short periods of time, tilting or rolling is not exacerbated by side-to-side air transfer.
In another aspect of the invention, both airflow discs attain a nonrestrictive state to promote rapid dumping of air simultaneously from the suspension elements to lower the ride height of the vehicle.
In a third aspect of the present invention, the airflow discs are easily installed and maintained in conventional valve bodies. The airflow discs are disposed within the suspension ports between an internal seat of the valve body and an external fitting associated with an air supply line leading to the suspension elements.
In a second embodiment of the invention, a system or pneumatic circuit of solenoids and one-way valves actively restrict side-to-side air transfer. Suspension elements on opposite sides of a vehicle, a supply port and dump port are plumbed into a system including solenoids and multiple check valves. A first solenoid may be selectively actuated (a) to allow air into the suspension elements through the supply port or (b) to prevent air from escaping the system through the supply port. A second solenoid may be selectively actuated (a) to dump air from the suspension elements through the exhaust port or (b) to prevent air from escaping the system through the exhaust port.
In this second embodiment, the check valves are oriented in the system so that when suspension elements on one side of the vehicle exhaust air therefrom, such as during cornering, that air is restricted by the check valves and will not rapidly transfer through the system to the suspension elements on the other side. The solenoids act in concert with the check valves to restrict side-to-side transfer, and prevent air from being lost or input into the system during side-to-side transfer and under even-load conditions.
The check valves also act in concert with the solenoids to supply air to or dump air from the suspension elements. For example, when dumping air from the suspension elements, some of the check valves attain a non-restricting state and act in concert with the exhaust solenoid to allow air to dump from the system. Similarly, when supplying air to the suspension elements, different check valves attain a non-restricting state and act in concert with the supply solenoid to allow air to enter the system and fill the suspension elements.
These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.